@Nicknackwack Hi and welcome to the forum.
I wish somebody with more knowledge than I had replied to you, but feel you may find what little I know to be of use.
1. Yes, there are some medications which can cause auto-immune disfunction.
2. They tend to be ones for cancer rather than for heart failure.
I suffered what may be called a cascade effect following a health issue:
About 25yrs ago I was nagged into eating lower Fat/higher complex Carb. Then 5 yrs ago (having gained about 14 lbs, I was diagnosed in danger of imminent heart attack (by angiogram) and had 3x Cardio Artery Bypass.
Drs advised doubling down on Low Fat/High complex carb /high fruit& Veg way of eating + statins, BP drugs (despite low BP) etc.
Result was gained around another 14lbs and diagnosed T2D 2 yrs ago. Drs gave same spiel as before, but this time I wasn't dumb enough to fall for it.
Found this forum, went Low Carb reduced HbA1C (non-diabetic range) plus back to what I weighed in my 20's ( currently 70 yrs old).